Reflector-type lamps, such as multi-faceted reflector (MR) lamps and parabolic aluminized reflector (PAR) lamps, are well-known and are used in a wide variety of applications. In general, a reflector-type lamp includes a light source disposed adjacent to a reflector cup. The light source may include one or more light emitting diodes (LEDs), a gas discharge light source such as a fluorescent tube (e.g., in a compact fluorescent (CFL) lamp), and/or a high-intensity discharge (HID) light source. The interior surface of the reflector cup may be provided with a reflective coating and/or may be formed from a reflective material such as aluminum. Light from the light source may be imparted on the interior surface of the reflector cup and reflected outward from an end of the reflector cup. The interior surface of the reflector cup may take a variety of shapes, e.g. generally paraboloid, ellipsoid, sphero-ellipsoid, etc., and controls the direction and spread of light cast from the lamp.
FIG. 1 includes an exemplary plot 300 of light output intensity (candela) vs. angle (degrees) illustrating the simulated performance of a conventional parabolic reflector lamp that includes: six LEDs providing 100 lumens (lm) output each (600 lumens total) in a rectangular alignment; a reflector cup having 90% mirror interior surface, a 30 mm diameter, and approximately 17 mm length; and a phosphor shell with a 1.7 index of refraction, 4 mm outer radius and 3 mm inner radius. The plot 300 was generated by a simulation using 1,000,000 rays output from the light engine and produced a 4 Pi space efficiency (the total power with the reflector divided by the total power without the reflector) of 91%, indicating that 91% of the 600 lumens from the LEDs were directed out from the reflector cup. Also, as shown, the simulated lamp exhibits a maximum central beam candle power (CBCP), defined as the lumens per solid angle at a radiation center (0 degrees in the illustrated plot), of about 1415 candela (cd) with a beam angle at the full-width half-maximum (FWHM) luminance value (707.5 cd) of about 28.9 degrees.